multi: add random coin selection

lnwallet/btcwallet/btcwallet.go

@@ -647,7 +647,8 @@ func (b *BtcWallet) SendOutputs(outputs []*wire.TxOut,
 	}
 
 	return b.wallet.SendOutputs(
-		outputs, nil, defaultAccount, minConfs, feeSatPerKB, label,
+		outputs, nil, defaultAccount, minConfs, feeSatPerKB,
+		b.cfg.CoinSelectionStrategy, label,
 	)
 }
 
@@ -697,7 +698,8 @@ func (b *BtcWallet) CreateSimpleTx(outputs []*wire.TxOut,
 	}
 
 	return b.wallet.CreateSimpleTx(
-		nil, defaultAccount, outputs, minConfs, feeSatPerKB, dryRun,
+		nil, defaultAccount, outputs, minConfs, feeSatPerKB,
+		b.cfg.CoinSelectionStrategy, dryRun,
 	)
 }
 
@@ -1100,7 +1102,10 @@ func (b *BtcWallet) FundPsbt(packet *psbt.Packet,
 
 	// Let the wallet handle coin selection and/or fee estimation based on
 	// the partial TX information in the packet.
-	return b.wallet.FundPsbt(packet, keyScope, accountNum, feeSatPerKB)
+	return b.wallet.FundPsbt(
+		packet, keyScope, accountNum, feeSatPerKB,
+		b.cfg.CoinSelectionStrategy,
+	)
 }
 
 // FinalizePsbt expects a partial transaction with all inputs and outputs fully

lnwallet/btcwallet/config.go

@@ -74,6 +74,10 @@ type Config struct {
 
 	// LoaderOptions holds functional wallet db loader options.
 	LoaderOptions []LoaderOption
+
+	// CoinSelectionStrategy is the strategy that is used for selecting
+	// coins when funding a transaction.
+	CoinSelectionStrategy wallet.CoinSelectionStrategy
 }
 
 // NetworkDir returns the directory name of a network directory to hold wallet

lnwallet/chanfunding/wallet_assembler.go

@@ -250,7 +250,9 @@ func (w *WalletAssembler) ProvisionChannel(r *Request) (Intent, error) {
 			"sat/kw as fee rate", int64(r.FeeRate))
 
 		// Find all unlocked unspent witness outputs that satisfy the
-		// minimum number of confirmations required.
+		// minimum number of confirmations required. Coin selection in
+		// this function currently ignores the configured coin selection
+		// strategy.
 		coins, err := w.cfg.CoinSource.ListCoins(
 			r.MinConfs, math.MaxInt32,
 		)